To fight a mosquito, maybe you’ve got to be a mosquito — at least that’s the hope behind one of the proposals to try to combat the Zika virus.

With the mosquito-borne disease creeping toward the U.S. mainland, British company Oxitec says one way to stop it is with genetically modified male insects, programmed to produce offspring that die before adulthood.

Oxitec says no adults means no spread for the Aedes aegypti mosquito, which carries the Zika virus. They hope to give their plan a test in Key Haven, Florida, and say success against Zika could also cut the rate of dengue and yellow fevers.

“I’ve yet to find the ‘Save the Mosquito’ society,” Oxitec CEO Hadyn Parry said in a recent interview. “No ones likes mosquitoes, and this one is an invasive species. It shouldn’t be there.”

Yet a vocal crop of Florida activists say the company is trying to test a new product without full consent from the community. They worry that the release of genetically modified organisms will result in unintended consequences for the human population and environment while deterring tourists, who are vital to the local economy.

“I’m angry now. They’re doing it against the will of the people,” said Mila de Mier, a Key West resident who started a petition against the trial.

The Food and Drug Administration recently said Oxitec’s proposal did not appear to pose a significant risk to humans and the local environment, though last week it gave the public an extra month, through May 13, to comment on its findings before final approval.

Oxitec’s trial could last up to a year and release millions of mosquitoes into a small, multiblock area of Key Haven.

The proposal has been wending its way through the federal regulatory process since 2011, when a local mosquito control director asked the company for help in controlling dengue, a flulike illness that can be lethal in severe cases.

The emerging Zika threat has breathed new life into the proposal. Though many who have been infected do not show symptoms, the virus has been linked to a dramatic surge in the number of babies born with abnormally small heads in Latin America and a syndrome that can lead to paralysis.

The virus is spreading in Puerto Rico, and local transmission could hit the U.S. mainland within months.

“Zika presents a very clear and present threat. And really, there isn’t any time to waste,” Mr. Parry said.

Oxitec’s male aegypti have a self-limiting gene that causes them to mate with wild females and produce offspring that cannot mature into adults. The technology reduced wild mosquito larvae by about 90 percent during trials in Brazil, the Cayman Islands and Panama, compared with 30 percent to 50 percent eradication from spraying, Mr. Parry said.

The males it would release don’t bite people, Oxitec says, and wild females typically mate only once in their short life spans, so the technique slashes the overall population.

“The fight against mosquito-borne diseases has been going on for over a century,” said Amesh Adalja, senior associate at the University of Pittsburgh Medical Center’s health security division. “Genetically modified mosquitoes are a potentially path-breaking tool that will improve human life.”

Among the 1,000-plus comments submitted to the FDA so far, one mocking supporter said opponents probably don’t know why it rains, to say nothing of a mosquito’s life cycle.

Others said they wouldn’t travel to Florida as long as genetically modified insects are flying around. One said it is “extremely irresponsible to conduct such an experiment where the risks are unknown and cannot be reversed.”

More than half of Americans overall, 56 percent, say they moderately or strongly support the release of genetically modified male mosquitoes, according to a recent poll by The Associated Press-NORC Center for Public Affairs Research. Sixteen percent moderately or strongly oppose the idea, and about a quarter have no stance.

“In my view, the public is mostly supportive of the program as long as we do our homework,” said Phil Goodman, a commissioner on the Florida Keys Mosquito Control District’s board, which must approve the Oxitec contract after the FDA speaks. “However, there is a very vocal minority in my view that has dominated the media on this.”

Another commissioner, Stephen K. Smith, said he was accosted at the post office by people who were upset about the project.

“People come up to me, and they’re very hostile,” he said, though others will approach him and say, “I had dengue. Do what you have to do.”

Given regulatory delays, the trial may not start until the fall — if it does at all.

Oxitec would produce eggs in Oxford, England, and ship them to Marathon, Florida, to incubate in the lab before they are released in Key Haven.

Once they are ready for release, a truck loaded with clear plastic containers of the modified insects will amble down the road and puff out the bugs with a fan.

The modified insects contain a fluorescent red protein that can be used to detect in the lab which mosquitoes belong to Oxitec. By measuring the predominance of mosquitoes with the distinctive marker, the company can get a sense of whether it is winning the battle in distinct sectors of the trial area.

“You get this constant, real-time readout of how successful you’re being,” Mr. Parry said. “If you need to release more, you release more.”

Mr. Smith said the technique appears to be “good science” and could be an effective tool in the Florida Keys‘ arsenal against mosquitoes.

“But if there is any unanswered questions or any responsible margin of doubt, I would probably not cast a vote in support,” he said.

Ms. de Mier, whose Change.org petition against the project has attracted more than 164,000 signatures, said Oxitec should try its technology where Zika is already circulating.

Dengue hasn’t been around for years, she said, and the community is dotted with well-manicured lawns and homes that employ air conditioning, reducing their vulnerability to disease-carrying aegypti.

She said another groundbreaking technique, injecting Wolbachia bacteria into the mosquito population, is a better way to rein in viral transmission, and that she will go to court if the Oxitec project proceeds.

“This is my family and this is my community, and we’re living in a democracy,” she said.

She also worries that another breed of mosquito, the Asian tiger, will fill any void left by the trial, or that modified aegypti will mutate in a way that allows them to survive.

Oxitec, which has called those fears unfounded, reserved meeting rooms at a Key West hotel so that members of the public can pepper them with questions Monday and Tuesday, part of an ongoing series of meetings and town halls to allay public concerns.

“We will have some people we will never convince because that’s just life, really, and it’s a shame,” Mr. Parry said. “But I think there’s an awful lot of people who are supportive of this.”